Processing of HIV envelope glycoproteins: The intracellular transport and processing of HIV gp16O has been investigated using wild-type and env mutants of molecularly cloned virus. Pulse-chase experiments in conjunction with a variety of biochemical analyses were conducted on cells acutely infected with virus stocks or transiently transfected with wild-type or mutagenized proviral DNA clones. These studies indicate that the intracellular transport and processing of the gpl6O env precursor polyprotein proceed via the rough endoplasmic reticulum (ER) and the various Golgi compartments. The formation of oligomeric gpl6O structures within the ER may be required for transport; however, appropriate folding of the oligomerized gpl6O is critical for accurate glycosylation, cleavage, and incorporation into progeny virons. Structure/function analyses of the HIV vif and vpu proteins: The HIV vif protein has previously been shown to be critical for virus-mediated infections. This 23 kDa protein is neither particle-nor membrane-associated and exists in cells in very low concentrations. The vif protein does not form oligomeric structures in infected cells, nor is it modified post-translationally. In contrast, large quantities of the HIV encoded vpu protein are synthesized during productive infection. Vpu is an integral membrane protein, is phosphorylated, and forms homopolymeric complexes, most likely tetramers, in infected cells. The interaction of vpu with other viral or cellular proteins is presently under investigation.